I just bought a compression tester and got these numbers:
#1 270
#2 265
#3 270
#4 272
This was with a warm engine, WOT & fuel pump disabled. When I bought the car I was told that the CR was 11.1:1 but have had no way to verify it. The motor has about 24k miles since build and is a B18C1 bottom end from a '96 GS-R with B16A pistons & new OEM rings, a B16A head with CTR cams, Portflow inner & ITR outer springs, OEM head gasket. The question is: Can the ACTUAL compression ratio be calculated from these compression numbers? Anybody got a GUESS?

 

Those rumbers seem a little higher than 11:1.

With the b18c1 bottom, b16 pistons, and b16 head, you should have a compression ratio of 11.42:1.

 

those are some really high numbers...
i do not know how to calculate the compression ratio....but also interested to learn...

bump

 

Here's a link to a CR calculator http://www.c-speedracing.com/howto/c.../compcalc.html but I'm interested in what these compression numbers equate to as an ACTUAL CR.